Such a system is described in, e.g., DE 10 2004 047492 A1. The known publication also discloses an automatic plug coupling system in the region of a “fifth wheel” semi-trailer coupling, which automatic plug coupling system is intended to replace the customary manually manipulated plug couplings.
DE 101 59503 A1 describes a monitoring and control device for a tractor and semi-trailer combination, wherein the tractor has a remotely controllable fifth wheel coupling, and the semi-trailer has at least one electrically operated device, such as a support jack. A control device which is electrically connected to the fifth wheel coupling is disposed on the tractor, and a communications device which is wirelessly connected to the control device is disposed on the semi-trailer.
A fundamental drawback of the known system is that the parking brake is not applied to the semi-trailer after the supply lines are interrupted until a certain time interval has passed. One skilled in the art understands the terms “braking” and “application of the brake(s)” to mean actuation of the typically spring-loaded parking brake of the trailer immediately prior to de-coupling of the tractor from the trailer. For this process, the driver manually opens a ventilation valve which is in the braking circuit of the trailer, so that the brake circuit is shifted to an unpressured state, and the spring system in the spring-loaded brake causes the parking brake to engage. With an automatic plug coupling system, when the tractor is de-coupled from the trailer the plug halves of the tractor-side supply circuit and the trailer-side brake circuit are automatically separated, and thereby the brake circuit is necessarily de-pressurized. However, with such an arrangement, there may be a time lag between the separation of the plug halves and the engagement of the parking brake. This carries the risk of relative movement of the trailer, or in some cases backward movement of both the tractor and trailer.